STATE HORTICULTURAL COMMISSION 
SB 951 

.C2 ELLWOOD COOPER, Commissioner 

Copy 1 



FUNGI AND 
FUNGICIDES 




SACRAMENTO 
W. W. SHANNON, - - SUPT. STATE PRINTING 

190S 



<& 



CALIFORNIA STATE COMMISSION OF 
HORTICULTURE. 



ELL, WOOD COOPER Commissioner Santa Barbara. 

JOHN ISAAC Secretary San Francisco. 

ED. M. EHRHORN Deputy Mountain View. 

E. K. CARNES Assistant Deputy Riverside. 

O. E. BREMNER... Second Assistant Santa Rosa. 

GERTRUDE BIRD Stenographer Sacramento. 



OFFICE: 

Room 41, State Capitol, Sacramento. 

Branch Office, Room 11, Ferry Building, San Francisco. 



FUNGI AND FUNGICIDL5. 



Growing plants are liable to the attacks not only of insects, 
but also of parasitic fungi. The peculiar maladies known as 
fungous diseases are produced by the rapid development of the 
parasitic fungi. It is estimated that in the United States alone 
the annual loss from these minute vegetable organisms runs 
into millions of dollars. 

Fungi belong to the so-called lower plants, among which are 
the toadstool, mushroom, molds, mildews, rusts, smuts, blights, 
etc. A fungus may attack only dead tissue or decaying matter, 
as is the case with mushrooms or toadstools, or it may attack only 
animal life, as is seen in the fungus which destroys the house 
fly and the chinch bug. But the most important class of para- 
sitic fungi with which the fruit-grower has to deal are those 
which attack the live tissue of plant life — those which check 
the growth of trees, attack and spot fruit, and even cause an 
early decay or a total loss before the crop is harvested. 

Fungi are plants, much the same as trees, grass, etc., the 
only difference being that they do not have the green coloring 
matter, or chlorophyll, of the latter. The seeds, called spores, 
are more simple and are exceedingly minute (microscopic). 
They are produced in numbers which appear almost incredible 
to those not versed on the subject. 

Fungi are divided into two groups: the internal and the 
external. The internal fungi send their germ tubes into the 
skin of the leaf, fruit, branch, or root, and the branching 
threads (mycelium) develop entirely within the tissue of the 
host plant. This group includes some of our worst species, such 
as peach-leaf curl, anthracnose, brown rot, shothole fungus, 
and all the grain smuts. 

The external fungi are surface feeders, their mycelium spread- 
ing over the surface of the fruit, leaf, or branch, as the case 
may be, and are easily controlled by the use of sprays. To this 
group belong the powdery mildews of the apple, grape, rose, 
gooseberry, etc. 



FUNGf AND FUNGICIDES. 



It will be readily seen that quick action, perseverance, and 
good judgment on the part of the grower are necessary to 
obtain satisfactory results. Especially is this true of the 
internal fungi, which must be attacked before the germ-tube 
enters the tissue. 

PEACH-LEAF CURL. 

In some seasons this fungus is very severe, and on some 
varieties of peach more than on others. It can be easily 
recognized by the abnormal growth of the leaf, which becomes 
leathery, highly colored, and sometimes resembles a seed-pod 
more than a Leaf. 

In winter use the lime-sulphur-salt wash or the Bordeaux 
mixture (formula A). 

Just as the buds are swelling use the Bordeaux mixture 
(formula B). 

APPLE OR PEAR SCAB. 

This is one of the most common diseases of pomaceous fruits 
the world over. It does not reduce the crop, nor does it seem to 

affect the vitality of the 
tree, but it injures the 
quality of the fruit, mak- 
ing it unsalable. The 
grower knows too well 
that a scabby or a de- 
formed pear has no sale 
in the market or at the 
cannery, in fact is only fit 
for hog feed; therefore, 
the utmost vigilance and 
greatest care should be 
exercised in the applica- 
tion of remedies to check 
this disease. The first 
appearance of the scab is 
seen upon the new growth 
and small fruit as a velvety spot: The disease is easily recog- 
nized, and if not soon checked the velvety spots on the fruit 
continue to spread until they have the appearance of black, 
scabby, corky blotches. As the pears grow, the development 
of the affected side is arrested, but the healthy side continues 




Fig. i. The effect of the fungus on one and 
two-year-old pear branches and Leaves. 



FUNGI AND FUNGICIDES. O 

to develop very fast and begins to twist or double over the 
affected side, making a very ugly looking, misshaped fruit. 

Spray with the lime-sulphur-salt wash as late in winter as 
possible. 

Spray with the Bordeaux mixture (formula A) while the 
buds are unfolding. If the season permits, a second and third 
spraying, ten days apart, using formula B, will prove beneficial. 



SHOTHOLE FUNGUS. 

This disease has, of late, become very prevalent, attacking 
all the stone fruits, and has been especially destructive to the 





Fn ;. 2. Appearance of the fungus on an apple. 



Fig. 



A blotch— enlarged. 



apricot. It makes its appearance upon the leaves, forming 
reddish-brown spots, which, when mature, shrink from the 
surrounding tissue and are blown away, leaving the leaf 
perforated. When the fungus attacks the fruit, it first appears 
as minute red pimples, which are very often mistaken for scale 
insects. These soon develop and burst open at the top, the 
new spores escaping and spreading the disease. The old spot 
forms a scab, which spreads and joins others, and soon the 
surface becomes very rough, rendering the fruit unsalable. 

Spray with the lime-sulphur-salt solution in winter, and use 
the Bordeaux mixture (formula B) just when the buds are 
swelling. If the lime-sulphur-salt remedy is not used, then 
the Bordeaux mixture (formula A) should be applied as early 
in the season as possible. 



b FUNGI AND FUNGICIDES. 

BROWN ROT. 

The brown or fruit rot of stone fruits is known in but few 
Idealities in the State. Wherever this disease occurs, its pres- 
ence is shown by the ashy gray spores on the surface of the 
fruit. Sometimes, where several fruits are clustered together, 
a small brown spot appears and rapidly spreads until the 
whole becomes shrunken, soft, and discolored. The interior 




Fig. ■",. Tear crackin 



Fig. 6. Leaf blight. 



of fruits which do not indicate much outward attaek will show 
a brownish, rotten appearance when cut open. 

Wherever the disease exists, care should be taken to gather 
all diseased fruit, generally known as mummied fruit, which 
may cling to the fruit spurs or fall to the ground, as the spores 
thereon will infect the next year's crop. 

The same remedies as are used for pear seal) will check this 
disease. 



FUNGI AND FUNGICIDES. / 

POWDERY MILDEW OF APPLE, PEACH, AND OTHER TREES. 

During the summer months one may notice the leaves and 
new growth of fruit trees covered with a thick, white, felt-like 
covering. These are the mycelium of the powdery mildew 
fungus. This fungus belongs to the external group, the 
mycelium of which live on the outside of the plant and do not 
enter the tissue of the leaf. Early in the fall of the year the 
winter spores are developed and consist of very minute, round, 
black masses, which remain on the fallen leaves or twigs dur- 
ing the winter and from which start the next season's brood. 

Use the ammoniacal solution of copper carbonate when the 
leaves first open, and in very bad cases repeat three or four 
times at intervals of fourteen days. 

BITTER ROT OF THE APPLE. 

This fungus has appeared in various apple districts. The 
time to spray for it is when it first makes its appearance. 
This disease can be easily recognized by the presence of small 
blackish pustules scattered over the surface of the apple. 
These are the fruiting spots of the fungus. The mycelium 
enter the pulpy tissue of the fruit and cause the rot to appear 
in little brown specks underneath the skin. 

In very bad cases the first spraying should be followed by a 
second and third spraying at intervals of two weeks, using the 
ammoniacal copper carbonate solution. 

PRUNE-LEAF RUST. 

The leaves of the prune and other stone fruits are often 
attacked by reddish spots on the surface and yellowish-brown 
spots on the under side. Sometimes this attack is so severe 
as to cause the dropping of the foliage. 

Spraying with the Bordeaux mixture (diluted formula) just 
after the buds start, and continued at intervals of ten or 
fourteen days during the growing season, will do much toward 
checking the fungus. 

PEAR BLIGHT. 

This disease, while not belonging to the group of fungous 
diseases on which we are treating, has become so important in 
this State and is doing such destructive work that allusion to 



8 FUNGI AND FUNGICIDES. 

it in this connection is imperative. The pear blight is caused 
by a bacterium discovered by Prof. T. J. Burrill, of Illinois, 
and by him named Bacillus amylovorus. Its point of entry 
into the tree is usually through the blossoms, although in some 
cases it may find entry through wounds or abrasions in other 
portions. The whole of the pomaceous family, including 
apples, medlars, hawthorns, and quinces, is subject to attack, 
but the pear especially so, and the tenderer varieties, as the 
Bartlett, most of all. This disease has received marked atten- 
tion from the Department of Agriculture at Washington, D. C, 
on account of the serious inroads it has made in the pear sec- 
tions of the East, and Prof. M. B. Waite has made an especial 
study of it for many years past. In response to an invitation 
from the Commission of Horticulture last fall, Professor Waite 
was detailed to study the disease in California, and under his 
direction a series of experiments has been made. So far the 
only method of fighting this disease, and the one which has 
been in vogue for many years in the East, is to cut out the 
affected portions of the tree well below the point of infection. 
An important feature of this work is the disinfection of the 
tools used in the cutting-out process. Unless this is properly 
done, the tools themselves may become the medium of distribu- 
tion of the disease. Professor Waite is positive in his assertion 
that if the work of cutting out the infected portions is con- 
scientiously and generally performed, there is little danger to 
be apprehended from this disease. 

GOOSEBERRY MILDEW. 

In some sections of the State it is almost impossible to raise 
good gooseberries, on account of mildew. This fungus appears 
in the spring upon the newly developed leaves and buds, and 
later appears as a white powdery mass, caused by the numerous 
summer spores. Later in the season it attacks the young- 
berries, which are rendered unmarketable, or in very bad cases 
the entire crop drops prematurely. 

Spray with a solution of potassium sulphide when the leaves 
commence unfolding, and repeat in from two to three weeks. 

During the winter remove all old canes and spray with the 
Bordeaux mixture (formula B). 



FUNGI AND FUNGICIDES. 



ANTHRACNOSE. 

Affecting the Raspberry, Blackberry, and Rose. 

This fungus appears as small reddish-purple spots upon the 
canes and leaves in the spring and early summer. These spots 
are scattered over the surface of the new growth near the 
ground, and have a distinct purplish margin, representing the 





Fig. 7. Rose leaf black spot. 



Fig. 8. Strawberry leaf blight. 



division between the healthy and diseased tissue. -As the 
season advances these spots increase in size, and, merging with 
others, form irregular, longitudinal blotches, which in very 
bad cases girdle the cane. 

Use the Bordeaux mixture (diluted formula) before the 
leaves open, and repeat at intervals of two weeks, spraying the 
canes which are starting out of the ground. 

Removing the old canes and burning them will greatly 
reduce the disease. 



10 FUNGI AND FUNGICIDES. 

ORANGE RUST. 

This disease is familiar to most growers of blackberries and 
raspberries. The disease becomes noticeable soon after the 
leaves expand in the spring, turning them a golden color. 
Soon small orange-colored spores appear on the surface of the 
leaves. From these spores develop the winter spores, which 
.spread to the growing shoots just starting from the ground and 
remain there until spring, to again infest the plant. 

All diseased canes should be cut and burned whenever dis- 
covered. Spraying with the ammoniacal copper carbonate 
.solution will prove helpful, if applied on the winter spores. 

ONION MILDEW. 

California, with her large seed gardens, has suffered very- 
much from onion mildew in abnormal seasons. The seed 
onions carry the hibernating spores, which soon attack the new 
growth in spring. The disease is easily recognized by the 
grayish, velvety coating on the new tops and blossom stalks. 
If the land is to be used again for onions, all tops remaining 
in the field after the seed has been collected should be burned, 
and should never be plowed under, as is generally practiced. 
Rotation of crops is much the safer preventive. 

Wherever practicable, the ammoniacal copper carbonate 
solution can be used to good advantage. 

BEAN ANTHRACNOSE. 

Young bean pods are often attacked by this disease, some 
varieties more than others. It can be readily recognized by 
small reddish-brown spots, slightly depressed, on the surface 
of the pods. These spots increase in size rather rapidly and, 
connecting with others, form long discolored blotches. The 
jx)d becomes stunted and the young beans are generally shriv- 
eled. Seed from diseased plants should never be used for 
planting, as the spores upon them will first infest the young 
growing plants and from them spread to the newly developed 
pods. 

Soaking the seed in a diluted ammoniacal copper carbonate 
solution before planting is a sure preventive. Spraying with 
the Bordeaux mixture (diluted formula) has given good results. 
Burning the old plants after harvest and making a clean cul- 
ture in general have much to do with a successful checking of 
the fungus. 



FUNGI AND FUNGICIDES. 11 



TOMATO ROT. 



When the fruit of the tomato is about half grown it is sub- 
ject to the attack of rot. The first appearance of this disease 
is a small blackish-brown spot, which rapidly increases in size. 
The underlying tissues of the fruit are destroyed by the fun- 
gous threads, and the side of the fruit affected becomes flattened. 

Wherever this disease appears it can be checked to a certain 
degree by thinning out the plants and allowing more sunshine 
to reach the fruit. 

Spraying with the Bordeaux mixture (formula B) when the 
fruit is first forming will often check the fungus. 

POTATO BLIGHT OR ROT. 

This disease attacks the leaves, stems, and tubers. It is first 
noticed upon the leaves by the sudden appearance of brownish 
or blackish areas, which soon become soft and foul-smelling. 
This disease generally occurs in our coast counties and other 
sections where plenty of moisture exists. The presence of a 
few successive hot, dry days in these districts checks its rapid 
development. 

Spraying with the Bordeaux mixture (formula B) when the 
growth just appears above ground, especially in sections where 
this fungus is known to exist, is very important. Affected 
potatoes should never be used for seed, and all vines remain- 
ing after harvest should be burned. 

POTATO SCAB. 

This is a very widespread disease, and is readily recognized 
by the dark, rough surface which occurs in spots all over the 
tubers. 

This disease can be successfully controlled by treating the 
seed potatoes in a solution of corrosive sublimate. Immerse 
them for a couple of hours in the liquid, and after their re- 
moval allow them to dry before cutting them for planting. 
All potatoes thus treated, if not planted, must be destroyed, as 
there is sufficient poison on them to make them dangerous to 
use as food or to feed to stock. 



12 FUNGI AND FUNGICIDES. 



ROOT KNOT. 



No fungous disease is easier recognized than this. The very 
prominent black or brown wart-like excrescences upon the 
trunk and roots, below ground, of all stone-fruit trees, readily 
reveal its presence. 

Cut away the knot in the fall or winter and allow the wound 
to dry, then with a swab apply a saturated solution of blue- 
stone to the affected part.* This may be repeated two or more 
times as long as the trees remain dormant. Never apply it to 
the tree when the sap is flowing. After the knots have been 
treated the soil is thrown back again, covering the exposed 
roots. The Bordeaux mixture (formula A), applied in a sim- 
ilar way, has also given good results. Instead of removing very 
large knots it is better to bore an inch hole to the center of the 
knot and fill this with either of the above solutions, which will 
permeate the tissues of the knot and cause it to drop off after 
a few months. 

OLIVE KNOT. 

One of the most serious diseases of the olive tree, in a few- 
counties of California, is the olive knot, or tuberculosis of the 
olive, as it is sometimes called, which, like the pear blight, is 
a bacterial and not a fungous disease. The tubercles, or knots, 
which give this disease its name, are found singly and in rows 
on branches of all ages. The bacteria which cause the disease 
form a colony in the tissue of the sap-wood, which appears 
like a small, transparent spot. This spot, when seen under a 
high-power microscope, is found to consist of many bacteria. 
From this spot soon develop, through different stages, the 
tubercle knots. On the trunks and larger brandies the knots 
generally attain a large size. 

The diseased parts of affected trees should be carefully re- 
moved and immediately burned. All wounds made by the 
removal of the disease should be dressed with an antiseptic 
paint. 

Cuttings from diseased trees should never be used for prop- 
agating purposes. 



*A saturated solution of bluestone is all that water will dissolve. But it 
is advisable to leave some undissolved bluestone in the bottom of the vessel, 
as this will indicate that the water has taken up all the bluestone it can. 




Fig. 9. Olive knot. 



14 



FUNGI AND FUNGICIDES. 



POWDERY MILDEW OF THE ROSE. 

This disease is too well known to the lovers of tea roses to 
need much description. It is the white powdery fungus which 
is so often seen on the new growth, leaves, and buds of the 
rose bush, marring the beauty and blasting the buds of many 
of our choicest varieties. 

If taken in hand when it first makes its appearance on the new 
growth, dusting with sublimed sulphur will check its spread. 
Spraying with the Bordeaux mixture (diluted formula), just 
before the new growth starts, will prevent its appearance. 




Fig. 10. Rose rust. 



ROSE RUST. 



This disease confines itself to the hybrid perpetual roses, 
and is easily recognized by the orange-colored spots on the 
under side of the leaves, which in very bad cases become 
entirely covered. 

After pruning rose bushes in the fall, they should be thor- 
oughly sprayed with the Bordeaux mixture (formula B). All 
leaves should be gathered and burned, as these contain the 
winter spores. If the fungus was very severe during the 
season, spraying again in the spring, just when the growth 
starts, with the ammoniacal copper carbonate solution or the 
Eau Celeste solution, will greatly aid in checking the trouble. 



FUNGI AND FUNGICIDES. 15 



FORMULAS. 



LIME, SULPHUR AND SALT. 

Unslaked lime 40 pounds. 

Sulphur 20 pounds. 

Salt 15 pounds. 

Water 60 gallons. 

Place 10 pounds of lime and 20 pounds of sulphur in a boiler 
with 20 gallons of water, and boil over a brisk fire for not less 
than one hour and a half, or until the sulphur is thoroughly 
dissolved. When this takes place, the mixture will be of an 
amber color. Next place in a cask 30 pounds of unslaked lime, 
pouring over it enough hot water to thoroughly slake it; and 
while it is boiling, add the 15 pounds of salt. When this is 
dissolved, add to the lime and sulphur in the boiler, and cook 
for half an hour longer, when the necessary amount of water 
to make the 60 gallons should be added. 

A much easier method of preparing the above wash is as 

follows: Make the sulphur into a thin paste with hot water; 

place the unslaked lime in a tight barrel and add the sulphur 

paste and from 10 to 15 gallons of boiling water. Cover the 

barrel with sacks and a wooden cover and let it stand. After 

the violent boiling has subsided, the mixture must be stirred 

thoroughly until all indications of boiling stop. Then add the 

salt and enough hot water to be able to strain the mixture into 

the spray tanks, and add the required quantity of boiling 

water. 

BORDEAUX MIXTURE. 

Formula A. 

Copper sulphate (bluestone) .. 8 pounds. 

Quicklime 10 pounds. 

Water 50 gallons. 

Formula B. 

Copper sulphate (bluestone) 5 pounds. 

Quicklime 6 pounds. 

Water 50 gallons. 

Diluted Formula. 

Copper sulphate (bluestone) 2 pounds. 

Quicklime 2 pounds. 

Water 80 gallons. 

Dissolve the copper sulphate in a barrel containing 10 to 12 
gallons of water. Slake the quicklime and thin it to a creamy 



HBKPRY OF CONGRESS 



16 FUNGI AND FUNGICIDES. g mQ ^j — ■ .. 

whitewash. Pour the whitewash very slowly through a wire 
screen into the copper solution. Stir the mixture thoroughly, 
and add enough water to make 50 gallons in all. Stir occa- 
sionally while applying as a spray to the trees. 

In the preparation of the Bordeaux mixture it is"ff£cessavy 
that the ingredients should be mixed in a wooden vessel. If 
an iron one is used the copper will go to the iron and the effect 
of the spray be largely neutralized. 

Apply the wash cold and as soon as possible after it is 
prepared. Never allow it to stand over night. 

AMMONIACAL COPPER CARBONATE SOLUTION. 

Copper carbonate ... ... 6 ounces. 

Ammonia 3 pints. 

Water -. 50 gallons. 

Dissolve the copper carbonate in the ammonia and add the 
water. 

Caution: Use no more ammonia than is required to dis- 
solve the copper carbonate. Ammonia is variable in strength, 
.and the amount required must be tested in practice. 

POTASSIUM SULPHIDE SOLUTION. 

Potassium sulphide 1 ounce. 

Hot water 2 gallons. 

Dissolve the potassium in hot water, and use as a spray 

when cold. 

EAU CELESTE SOLUTION. 

Copper sulphate 2 pounds. 

Ammonia 1 quart. 

Water 50 gallons. 

Dissolve the copper sulphate in 6 gallons of water, using a 
wooden vessel, then add one quart of ammonia and sufficient 
water to make 50 gallons of wash. 

CORROSIVE SUBLIMATE SOLUTION. 

Corrosive sublimate 2A ounces. 

Hot water 2 gallons. 

Dissolve the corrosive sublimate in the water, let it stand 
for about 10 hours, and then add sufficient water to make 15 
gallons of spray. 



! 



LIBRARY OF CONGRESS 

0000AA^fi340 




